Device for supplying water for the further alluviation of fibres in strainers



; Nov. 16, 1965 v s. o. VALTANEN ETAL 3,217,937

DEVICE FOR SUPPLYING WATER FOR THE FURTHER ALLUVIATION 0F FIBRES INSTRAINERS Filed Dec. 19, 1963 2 Sheets-Sheet l 16, 1965 s. o. VALTANENETAL 3,217,987

DEVICE FOR SUPPLYING WATER FOR THE FURTHER ALLUVIATION 0F FIBRES INSTRAINERS Filed Dec. 19, 1963 2 Sheets-Sheet 2 A MIR mum Ill-BIL lllllllIII-HI IIIIIIIN MID! VII. mm mm I17 I17. llll'fl lull, lll'" UnitedStates Patent Office 3,217,987 Patented Nov. 16, 1965 3,217,987 DEVICEFOR SUPPLYTNG WATER FOR THE FURTHER ALLUVIATIGN F FIBRES IN STRAINERSSeppo Olavi Valtanen and 011i Juhani Punttila, Karhula, Finland,assignors to A. Ahlstriim Osakeyhtio, Karhula, Finland, a company ofFinland Filed Dec. 19, 1963, Ser. No. 331,814 6 Claims. (Cl. 239539) Thefollowing invention consists of a device for supplying water for thefurther alluviation in strainers of fibres, such as cellulose pulps. Itis intended particularly for centrifugal strainers, and its purpose isto distribute the water supplied in the manner desired longitudinallyalong the strainer, and to ensure that the distribution device can beadjusted during the operation.

Similar devices for supplying water for alluviation, in which the rotorshaft has been bored hollow along its length and supplied with radialholes through which the water flows into the strainer, are prior known.By carefully selecting the size and the position of the holes, the exactdistribution of fresh water required for a particular condition ofoperation can be achieved, but it is impossible to alter thisdistribution during operation. So that the supply of fresh water can beadjusted to a certain extent, the device has also been divided intosections enabling the ratio between the quantities of water in thedifferent sections to be varied, but even here, the distribution withineach section remains constant during the operation, and cannot bemodified.

The purpose of the present invention is to achieve greater adjustabilityin the supply of water for the further alluviation of fibres instrainers by means of a hollow rotor shaft furnished with holes. Theprincipal characteristic of the invention is that in or around thehollow shaft lies a sleeve provided with holes running axially and andmovable in an axial direction, the holes in the shaft and sleeve beingarranged in coincident axial rows but having different dimensions, atleast in the axial direction, while the centres of the holes reckonedfrom the middle point of the rows towards both ends are displaced inrelation to each other so that when they are in a position in which themiddle points of the rows of holes in both the shaft and the sleevecoincide, the flow through each pair of holes is of equal magnitude, butwhen the sleeve is displaced in either direction, said flow varies indifferent degrees through each pair of holes in the row. The distancebetween the centres of the holes in the sleeve in the direction of theshaft is best obtained from the following formula:

in which L is the distance between the centres of the holes at the outerends of the row in the rotor shaft, x is the nominal value of thedifference between the axial dimensions of the holes in the shaft andsleeve, and n is the number of holes minus 1 in a row; when the holes inthe sleeve are bigger than those in the shaft, x is taken to have a signwhen the outer edge of the larger holes at the farther ends extendsbeyond the outer edge of the smaller holes at the farther ends, and x istaken to have a sign when the outer edge of the outer holes in both rowscoincide. When the holes in the shaft are bigger, the signs of x are thereverse of those given under the above two conditions.

One embodiment of the invention adapted for a centrifugal filter isshown as an example in the accompanying drawing:

FIG. 1 is a longitudinal section of a centrifugal strainer in a deviceaccording to the invention;

FIGS. 2-4 shows the distribution of alluviation water through threedifferent arrangements of the holes in the sleeve in relation to theholes in the rotor shaft.

No. 1 in FIG. 1 is the rotor shaft, bored hollow longi tudinally andprovided with holes 2. Alluviation Water enters through the inlet 3. Thequantity of this water can be regulated in a manner which need not bedescribed here. The inlet 3 is joined to the shaft 1 by a packing box 4.Inside the shaft is a sleeve 5, which is provided with holes and can bemoved axially. The sleeve 5 is joined by a spindle 6 to a socket 7 whichis furnished with cogs running along its length. The end of the spindle6 is carried in bearings 9 and 10 inside the socket 7, and rotates withthe shaft 1. No. 11 is a packing box.

The holes in the sleeve 5 are placed at slightly different intervalsfrom those in the shaft 1, as can be seen in FIGS. 24. FIG. 2 shows theaxially movable sleeve in such a position that all its holes are fullyopen. If the shaft holes are distributed evenly and are of equal size,the quantities flowing through are evenly distributed along the shaft,as shown in the graph above FIG. 2. FIGS. 3 and 4 show the sleeve inpositions in which the outer holes at one end of the row of holes in theshaft are fully closed, while those at the other end are fully open andthe intermediate holes are opened in varying degrees. Thus the open-holearea and flow of liquid through the shaft holes varies longitudinally,as can be seen from the graphs.

The holes in the shaft and sleeve can be of different dimensions anddistributed in different ways along their length. Any distribution offresh water quantities that is desired can thus be obtained, forexample, by fully opening one or more holes at one end of the row ofholes in the shaft, while all the others are fully closed. The shaftholes can lie in a direction other than a radial one.

The invention is not limited to the construction described abo e andshown in the drawings, but can be varied in many different ways. Forexample, the sleeve can be placed around the rotor shaft and providedwith cogs lying side by side running peripherally in the direction ofthe shaft, the cogs being in contact with a cogwheel which enables thesleeve to be moved in either direction.

What we claim is:

1. An improvement in a pulp screen including an annular screen and arotary impeller, a pulp stock inlet located axially with respect to saidimpeller, a hollow drive shaft having a series of axial rows of holes inits surface area and means to supply dilution water to said hollowshaft, a sleeve having telescoped relationship with and axially movablealong said shaft and provided with axial rows of holes coinciding inradial axial planes with rows of holes in said shaft, there being thesame number of holes in the rows thereof in the sleeve and in the rowsof holes in the shaft, and means to move said sleeve axially along saidshaft, the holes in the sleeve having different dimensions in thedirection axially of the sleeve and shaft compared to the holes in theshaft, while the centers of the holes reckoned from the middle point ofthe rows towards both ends are displaced in relation to each other insuch a way, that when they are in a position in which the centers of theholes in the axial center of the rows of holes in the shaft and sleevecoincide, the flow of dilution water through each pair of holes is ofequal magnitude, but when the sleeve is displaced in either directionwith respect to the shaft, said flow varies in different degrees throughthe communicating pairs of holes in the rows in the shaft and sleeve.

2. An improvement in accordance with claim 1 in which said sleeve islocated inside of said hollow shaft.

3. An improvement in accordance with claim 1 in which said sleeve islocated around said hollow shaft.

4. An improvement in accordance with claim 1,

wherein the holes in the shaft are similar and are spaced equaldistances along the length of the shaft, and wherein the holes in thesleeve are similar and are spaced equal distances along the length ofthe sleeve.

5. An improvement in accordance with claim 4, in which the distancebetween the centers of the holes in the sleeve in the direction of theshaft is disposed according to the formula L-l-x/n in which L is thedistance between the centers of the holes at the outer ends in the rowsof holes in the shaft, x the difference between the axial dimensions inthe holes of the shaft and sleeve, and n the number of holes minus 1 ina row, so that, when the holes in the sleeve are bigger in an axialdirection than those in the shaft, x has a sign when the outer edge ofthe larger holes at said farther ends extend beyond the outer edge ofthe smaller holes at said farther ends, and has a sign when the outeredge of the holes at said farther ends in both rows coincide.

6. An improvement in accordance with claim 1, comprising a spindleconnected to the sleeve, said spindle extending beyond said rotor.shaft,to a socket provided with a rack gear along its length connected to thespindle, and a cogwheel in mesh with the rack, whereby the said spindletogether with said sleeve can be shifted in either direction while theshaft is rotating.

References Cited by the Examiner UNITED STATES PATENTS 201,986 4/1878Bishop. 1,614,357 1/1927 Gamper. 1,843,715 2/1932 Gavino 239-4l73,032,239 5/1962 Whitley et al. 222486 M. HENSON WOOD, IR., PrimaryExaminer.

EVERETT W. KIRBY, Examiner.

1. AN IMPROVEMENT IN A PULP SCREEN INCLUDING AN ANNULAR SCREEN AND AROTARY IMPELLER, A PULP STOCK INLET LOCATED AXIALLY WITH RESPECT TO SAIDIMPELLER, A HOLLOW DRIVE SHAFT HAVING A SERIES OF AXIAL ROWS OF HOLES INITS SURFACE AREA AND MEANS TO SUPPLY DILUTION WATER TO SAID HOLLOWSHAFT, A SLEEVE HAVING TELESCOPED RELATIONSHIP WITH AND AXIALLY MOVABLEALONG SAID SHAFT AND PROVIDED WITH AXIAL ROWS OF HOLES COINCIDING INRADIAL AXIAL PLANES WITH ROWS OF HOLES IN SAID SHAFT, THERE BEING THESAME NUMBER OF HOLES IN THE ROWS THEROF IN THE SLEEVE AND IN THE ROWS OFHOLES IN THE SHAFT, AND THE HOLES IN THE SLEEVE SAID SLEEVE AXIALLYALONG SAID SHAFT, THE HOLES IN THE SLEEVE HAVING DIFFERENT DIMENSIONS INTHE DIRECTION AXIALLY OF THE SLEEVE AND SHAFT COMPARED TO THE HOLES INTHE SHAFT, WHILE THE CENTERS OF THE HOLES RECKONED FROM THE MIDDLE POINTOF THE ROWS TOWARDS BOTH ENDS ARE DISPLACED IN RELATION TO EACH OTHER INSUCH A WAY, THAT WHEN THEY ARE IN A POSITION IN WHICH THE CENTERS OF THEHOLES IN THE AXIAL CENTER OF THE ROWS OF HOLES IN THE SHAFT AND SLEEVECOINCIDE, THE FLOW OF DILUTION WATER THROUGH EACH PAIR OF HOLES IS OFEQUAL MAGNITUDE, BUT WHEN THE SLEEVE IS DISPLACED IN EITHER DIRECTIONWITH RESPECT TO THE SHAFT, SAID FLOW VARIES IN DIFFERENT DEGREES THROUGHTHE COMMUNICATING PAIRS OF HOLES IN THE ROWS IN THE SHAFT AND SLEEVE.